1. Field of the Invention
The present invention relates to machine tools and, more particularly, to a holder for supporting a removable cutting insert. Most particularly, the present invention relates to a holder having an improved clamping mechanism, wherein a cutting insert is quickly and easily indexable in one of a plurality of precision cutting positions.
2. Description of the Related Art
A conventional machine tool typically includes a spindle within which there is a combined holder and cutting insert. When the insert becomes dull, it is removed and replaced with a new cutting insert. Indexing the cutting insert makes it possible to reinsert the cutting insert in the same position.
One type of indexing, which achieves a position close to that of a previously used cutting insert, provides a flattened surface on one side of the cutting insert and a setscrew through the holder to bias against the flat surface. However, this structure does not accurately position the cutting insert because the setscrew only engages a small area of the flat surface. Moreover, there is no assurance that the cutting insert will properly engage the holder to assure stability of the cutting insert during a cutting operation.
Another type of indexing provides a groove in the cutting insert that cooperates with a pin passing through the holder. A setscrew bears against the surface of a depression formed in the cutting insert to force the groove into contact with the pin. In accordance with this design, the groove and pin cooperatively locate the cutting insert in a desired position. However, this design locates the cutting insert in a single position.
It is desirable in the machine tool art to be able to establish a machine setup for progressive machining operations. For example, this may involve having a first cutting insert make a desired cut. The first cutting insert is withdrawn from the holder and a second cutting insert is inserted into the holder to make another cut. Then, the second cutting insert is withdrawn from the holder and the first cutting insert is repositioned into the same position that it formerly occupied in the holder to duplicate the first cut. This machining operation is referred to as “repetitive positioning”. Repetitive positioning necessarily requires that the cutting insert be precisely locatable relative to the holder.
Additionally, it is desirable that a cutting insert be readily insertable into and removable from the holder so that various machine operations can take place with the maximum amount of efficiency. In other words, not only must the holder and cutting insert cooperatively provide for the repetitive positioning of the cutting insert, it is desirable that this be done very quickly.